Wi-Fi routers that power devices could boost Internet of Things

By Jack Loughran

Published Thursday, November 19, 2015

Wi-Fi routers that can power electronic devices could become the backbone of future smart homes according to University of Washington engineers.

The team that has developed the Power over Wi-Fi (PoWiFi) system has already demonstrated that it can provide energy to electronics such as a simple temperature sensor, a low-resolution grayscale camera and a charger for a Jawbone activity tracking bracelet.

"For the first time we've shown that you can use Wi-Fi devices to power the sensors in cameras and other devices," said Vamsi Talla, lead author on the study.

"We also made a system that can co-exist as a Wi-Fi router and a power source -- it doesn't degrade the quality of your Wi-Fi signals while it's powering devices."

The team of computer science and electrical engineers found that the peak energy contained in untapped, ambient Wi-Fi signals often came close to meeting the operating requirements for some low-power devices.

However, because the signals are sent intermittently, energy ‘leaked’ out of the system during periods of low Wi-Fi activity.

The team overcame this by introducing superfluous ‘power packets’ on Wi-Fi channels not currently in use.

This boosted the potential of Wi-Fi as a power delivery method without affecting the quality of the signal or speed of data transmission.

The team also developed sensors that can be integrated in devices to harvest the power.

The initial results were promising and demonstrated that the PoWiFi system could wirelessly power a grayscale Omnivision VGA camera from over five metres away, allowing it to store enough energy to capture an image every 35 minutes.

It also re-charged the battery of a Jawbone Up24 wearable fitness tracker from zero to 41 percent in 2.5 hours.

Although the current implementation is only suitable for low power devices, the team believes that the technology can be scaled up with further research.

"In the future, PoWiFi could leverage technology power scaling to further improve the efficiency of the system to enable operation at larger distances and power numerous sensors and applications," said co-author Shyam Gollakota.

The technology shows promise for the Internet of Things, enabling small, embedded devices and sensors to draw enough power to communicate with each other in a modern smart home.